Epigenome Analysis Of Sorghum Root And Leaf Under Drought Stress

Sorghum bicolor L.Moench is an annual grass of the grass family,a short-day C4 plant that is the fifth largest food crop after rice,maize,wheat,and barley and is drought,poor,and saline-alkali tolerant.Drought is an important cause of the loss of grain production worldwide,so it is of great practical significance to cultivate drought resistant varieties.More and more studies have shown that epigenetic regulatory mechanisms play an important role in plant development and stress response,but the epigenetic regulatory mechanisms in roots and leaves of sorghum under drought conditions remain to be studied.This project mainly takes sorghum as the research object and uses the joint analysis of RNA-seq,Ch IP-seq and MNase-seq to study the roots and leaves of sorghum under drought stress.The main conclusions are as follows:1、 Through transcriptome data analysis,8256 DEGs were obtained from roots and4214 DEGs from leaves of sorghum under drought stress.GO function analysis was conducted on the obtained DEGs,and it was found that the differential genes in roots and leaves were significantly enriched in GO functions such as heat stress response,cell wall,plasma membrane,external encapsulation structure,and transmembrane transporter activity.KEGG enrichment analysis of the obtained DEGs showed that the pathways related to plant drought resistance were enriched in the root differential genes and glutathione metabolism pathway and steroid hormone biosynthesis,while the pathways related to plant drought resistance were enriched in the leaf differential genes and plant hormone signal transduction pathway and MARK plant signal pathway.2、 Drought stress can significantly reduce the level of histone acetylation modification on the whole genome of sorghum roots and leaves,and the function of histone acetylation is to activate transcription.In addition,drought stress can significantly increase the level of histone methylation and histone variant in roots,and the function of histone methylation and histone variant is to inhibit transcription.3、 Through the analysis of the nucleosome signals in TSS region of sorghum under drought stress,it was found that the nucleosome signals in roots and leaves under drought stress were stronger than those in normal state in TSS region,and the combined analysis of genes involved in the change of nucleosome signals and differential genes showed that the expression of most genes involved in the enhancement of nucleosome signals was inhibited.4、 The histone modification results on differential genes showed that the modification levels of H3K9 ac,H3K27ac,H3K4me2 and H2 A.Z in root neutralization increased,while the modification levels of H3K9 ac and H3K27 ac in leaves decreased,and the rest had no significant changes.These results indicated that histone modification in roots could promote and inhibit the expression of differential genes.The leaves mainly inhibit gene expression.5、 The expression patterns of SbHMT,SbHDM,SbHAT and SbHDAC gene family members in sorghum under drought stress indicated that all four families had genes involved in drought stress induction,and the expression levels of Sb SDG12,Sb SDG28,Sb SDG53 and Sb SDG54 in the leaves of SbHMT family decreased under drought stress.The expression levels of Sb PRMT2,Sb PRMT3,Sb PRMT4,Sb SDG6,Sb SDG7,Sb SDG9,Sb SDG17,Sb SDG33 and Sb SDG38 decreased in roots under drought stress.The expression levels of Sb SDG4,Sb SDG21,Sb SDG39 and Sb SDG40 increased in roots under drought stress,while the expression levels of Sb SDG7,Sb SDG17,Sb SDG12,Sb SDG28,Sb SDG53 and Sb SDG54 were higher in leaves than in roots under drought stress.The expression levels of Sb SDG6,Sb SDG21 and Sb SDG55 in roots were higher than those in leaves.The expression of SbHDMA2,SbHDMA4,Sb JMJ1,Sb JMJ2,Sb JMJ3,Sb JMJ4,Sb JMJ5,Sb JMJ7,Sb JMJ8,Sb JMJ12,Sb JMJ13,Sb JMJ14 and Sb JMJ22 in sorghum SbHDM family was induced by drought stress.The expression of SbHAC1 and SbHAG4 in sorghum SbHAT family was induced by drought stress.The expression of SbHAG4 increased in leaves under drought stress,while SbHAC1 and SbHAG4 decreased in roots under drought stress.The expressions of SbHDA5,SbHDA11,Sb SRT2 and SbHDT2 in sorghum SbHDAC family were induced by drought stress,and the expressions of SbHDA5 and Sb SRT2 increased in roots under drought stress.In conclusion,this study obtained the regulation mode of histone modification under drought stress in sorghum through analysis,and selected genes related to drought stress from the gene family related to histone methylation and histone acetylation,providing important resistance gene resources for the study of histone modification function in sorghum drought resistance.